Glass composition

ABSTRACT

A GLASS COMPOSITION IS FORMED FROM ONLY THREE CONSTITUENTS-SILICA, ALUMINA, AND BERYLLIA. THE FIBERS FORMED FROM SAID COMPOSITION, ON CONVENTIONAL PRODUCTION EQUIPMENT, EXHIBIT IMPROVED MODULUS, TENSILE STRENGTH AND DENSITY OVER FORMERLY AVAILABLE TEXTILE FILAMENTS, AND SHOW PARTICULAR UTILITY IN REINFORCEMENT OF PLASTIC LAMINATES WHERE HIGH STRENGTH TO WEIGHT RATIOS ARE DESIRED AND IMPERATIVE, FOR EXAMPLE, IN NOSE CONES, ROCKET MOTOR CASES AND SUBMARINES.

g- 3, 1971 R. M. M MARLIN 3,597,246

GLASS COMPOSITION Filed March 31, 1967 3, 65 O5 B Q A] 0 C Z 3 INVENTOR. 5102 2 51/5 fi flfif/Pf/lf Mama/M Rep/"waved fly Mo/e Per 69/72 m ATTORNEYS "ni'ted States "ice 3590246 Patented Aug. 3, 1971 percent, are as shown: SiO 70.0%, Al O 12.5%, 3,597,246 BeO17.5%. GLASS COMPDSITIGN TABLE I THE EFFECT OF THERMAL TREATMENT Robert M. McMarlin, Newark, Ohio assiguor to Owens Com g Fibergias corpmfion ON TENsrLE STRENGTH AND MODULUS Filed Mar. 31, 1967, Ser. No. 627,460 int. Cl. C03c 3/04, 13/00 Batch melting Tensile, Modulus,

U.S. (:1. 10650 18 Claims ABSTRACT OF THE DISCLOSURE g A glass composition is formed from only three con- 22% stituentssilica, alumina, and beryllia. The fibers formed 532 from said composition, on conventional production equip- F ment, exhibit improved modulus, tensile strength and 700 density over formerly available textile filaments, and 2% iii show particular utility in reinforcement of plastic lami- 696 nates where high strength to weight ratios are desired and imperative, for example, in nose cones, rocket motor cases and submarines. 90 The batch melting time and temp, as the heading of the first column, is a phrase used to denote the time and temperature necessary to get homogeneity in small batch 1 Properties rechecked using a new batch of glass.

This invention relates to glass compositions and parglass melts. ticularly to glass compositions for forming glass fibers The table shows that for small glass batch melts the exhibiting three specific propertieshigh tensile strength, 25 physical properties improve when the glass composition high modulus of elasticity, and a low density. is melted at optimum conditions, wherein the batch-melt- This combination of physical properties becomes iming time is 24 hours at a temperature of 2900 F. When portant and is useful in reinforcement of plastic lamithe glass composition is melted below optimum condinates when light weight, high strength construction is tions, its tensile strength shows no great advantage over imperative. Glass fibers produced from the glass comconventional fibers of E-glass. positions of this invention meet this criteria and find use These results show that when the glasses of this inin the aircraft industry and particularly in reinforced mavention are commercially fiberized, careful temperature terials used in the construction of missiles, rockets, rocket control of the production melting unit must be mainmotor covers, satellites, and other space and deep subtained. Higher melting temperatures in production units mergence vehicles (submarines) and watercraft. reduces the long period of time required at the lower Commercial filament E-glass is typical of fibers possesstemperatures. For example, at temperatures of about ing high tensile strength that are used as reinforcement 3200 F. the melting time is approximately 4 hours to for plastic and resin laminated structures. E-glass has a insure homogeneity of the mixture. The melting time is virgin glass fiber tensile strength of 500,000 psi. and a also substantially reduced by the fact that larger quantities virgin fiber density of 2.54 g./cc. The use of the term of ingredients are used which insures a more complete virgin herein denotes that no sizing or after treatment mixing before the fibers are formed therefrom. has been applied to said fiber. FIG. 1 represents a phase diagram of the three com- It is one object of this invention to provide a glass ponent glass compositions bounded therein which are composition, that is fiberizable, having greatly improved within the scope of this invention. tensile strength and modulus and exhibiting a lower FIG. 2 is an enlargement of the area bounded in FIG. density. 1, which represents the ranges of glass compositions en- It is another object of this invention to provide a glass compassed in this invention. composition made only of three components, SiO A1 0 The SiO -Al O -BeO System of FIGS. 1 and 2 are and BeO, that is fiberizable and which fibers therefrom represented in mole percents. possess exceptionally good properties. Extensive studies of the region in the phase diagram It is a further object to provide a glass composition of FIG. 2 bounded by an imaginary line drawn through that is fiberizable and possesses a highly reactive surface points labeled A, B, C, D and an imaginary line drawn that readily couples with protective compositions such as through points E, F, G, H Were conducted. This region sizes, lubricants, finishes, various after treatments and is characterized by Al O /BeO mole ratios that range th lik from 0.50 to 1.00 and SiO mole percentages that range The components of the glass composition are present from 60.0-80.0. Glasses of these compositions, when in the following proportions, expressed in mole percent. melted under optimum conditions herein above described, The preferred ranges of proportions for each constituent produce the desired physical properties of high tensile are as follows; strength, high modulus and low density. Other compositions within the area of the large phase diagram of FIG. Oxide: Mole percent 2 also produced glass fibers having high tensile strength SiO 63.077.0 and high modulus. Ranges of compositions within this A1 0 10.0-20.0 area are as follows:

B60 r Oxide: Mole percent This range of proportions for each constituent was se- 66 2 22 lected only after a detailed study had been undertaken B and evaluated. e

*In the development of this invention it was found that The use of beryllia in glasses of the type described the eifect of the thermal treatment on tensile strength 70 yields improved properties of the fibers produced thereand modulus was very critical. The results for the glass from. Said fibers exhibit high modulus of elasticity and having the following composition, expressed in mole low density.

Glasses of high Youngs modulus are obtained when the interstices of a silicate network are filled with ions of high field strength. Beryllium is characterized as such an ion. Previous investigation has shown that such glasses are characterized by a low content of network formers, including silica and alumina. Compared on a cation-fora temperature for periods ranging from 424 hours. Cullet was formed by plunging the hot crucible into a water bath at room temperature. Fibers were obtained from the glass compositions by remelting the prepared cullet in a one-hole precious metal bushing capable of reaching temperature in excess of 3200 F.

TAB LE 11 II III IV V VI VII 70. U 68. 6 6'7. 7 70. 65. G 76. 6 17. 0 11. 7 14. 4 15. 0 14. 6 13. 4 13. 0 l9. 7 l7. 9 15. U 20. i 10. 7 2. 42 2. 37 2. 27 2. 40 2. 37 '2. 30 6 778 702 650 742 537 754 A O;,BeO mole ratio. 0. 7 1. 31 0. 59 0. 81 1. 0 0.72 l. 34 Modulus, p.s.i. 10 5 l4. 0 11. 0 13. 8 13. 5 12. 0 14. 2 l2. 8

Ionic size Field strength Because beryllium is so small in ionic size and possesses such a high field strength, glass compositions containing this element have enhanced devitrification and phase separation tendencies, but heretofore such tendencies have made fiberization of good quality fibers most difficult. Irrespective of these tendencies, good quality fibers were formed from compositions within the phase diagram of FIG. 2 by melting said compositions under carefully controlled conditions to obtain homogeneity before fiberforming.

Commercially, one method or apparatus by which the glasses of this invention may be melted under carefully controlled conditions to obtain a homogenized melt, is described in U.S. patent, Veazie, et a1. 3,264,076. Good quality fibers possessing very high tensile strength, high modulus, and low density were obtained from said homogenized melt.

Glass compositions have been prepared and samples tested as indicated in the following examples, wherein the ingredients are proportioned by mole percent. Said examples are shown as specific embodiments of this invention and are by no means limitations thereon.

EXAMPLES I-VII Each glass composition was prepared by dry mixing the appropriate oxides, which were of at least U.S.P. grade, in a double-cone agitator Wheel blender for approximately ten minutes. The dry batch was melted in precious metal crucibles. The melting temperatures utilized ranged from 2900-3200 F.; each glass was held at Examination of the data in Table II shows that Examples I-VII are glass compositions within the range of this invention. The low density glass has tensile strengths ranging from 127% to 156% that of commercial E-glass, and moduli ranging from 114% to 135% that of commercial E-glass, and fiber density ranging from 5 %ll% lower than that of commercial E-glass.

In glasses of the silica-alumina-beryllia type the most important single factor in raising the Youngs modulus, while maintaining low density, is the addition of beryllia. It has been determined by previous investigation that only in beryllia glass compositions does the density decrease, whereas other cations, including magnesium and calcium, increases the density of glass compositions. This factor of low density is not an inherent characteristic since the density of beryllium (1.85 g./cc.) is higher than that of magnesium (1.740 g./cc.) and calcium (1.415 g./cc.), but is dependent upon the role which the beryllium ion plays in the structure.

Because of its lower density the glasses of this invention inherently have a specific tensile strength and specific modulus of elasticity greater than that of E-glass. One method for relating or defining the specific tensile strength and specific modulus of elasticity is by the following formulae:

(1) Specific T.S.:T.S./p (2) Specific modulus Y/ p wherein T.S.=tensile strength measured in p.s.i. Y modulus of elasticity, p.s.i. =density, measured in #/in.

Following is a table showing the specific tensile strength and specific modulus for E-glass, S-glass and the glasses of this invention. S-glass, a magnesia-alumina-silica compoition, was included in this table to emphasize the improved properties of this invention, for S-glass is especially known for its high strength to Weight ratio. Also included in the table is a column showing the product of specific tensile strength and specific modulus.

TABLE III Tensile, Modulus, Density, Glass p.s.i.. 10 p.s.i., 10 lbs./in. TS/ 10- 371;, 10- TS/p x Y/ 10 E-glass 500 10. 5 0. 092 6. -13 1. 14 6. 1t) S-glass 700 12. 1 0. 000 7. 7 1. 38 10. 74 Example:

In the above table, the ratio of TS/ is used to denote the high strength to weight relationship. Y/p is used to denote the high bending or flex to weight relationship. The product of TS/ x Y/p is used by the Air Force Testing Laboratories as another criteria for rating diiferent glass compositions that find use in rocket motor chambers.

A look at Table III shows that the glasses of this invention exhibit exceptionally good strength to weight values, ranging from 115-163% that of commercial E-glass and in all cases but one exhibit better values, ranging from 102-114% that of S-glass.

The same can be said about the bending or flex to weight values of this invention. The glasses of this invention range from 121-145% that of E-glass and range from 108-120 that of S-glass.

The product of these two ratios (TS/ XY/ p) likewise shows that this invention produces fibers exhibiting exceptionally good values, ranging from 167-228% and from 109-131% that of E-glass and S-glass respectfully.

The glasses of this invention melt readily in existing commercial glass melting units. Commercial fiber forming processes comprises the steps of flowing a stream of molten glass composition from a melting source and attenuating said stream into fibers by mechanically pulling the stream with a pulling device. As the glass is attenuated, solidification takes place and fine diameter fibers are produced. Collet winders (Beach 2,391,870) and pulling wheels (Slayter et al. 2,729,027) are used as devices for mechanically attenuating fibers.

Certain glass compositions are difiicult to fiberize because of their rapid devitrification rate at or near the liquidus temperature. Because of their viscosity-liquidus relationship, it has been found desirable to have a viscosity of from 100-300 poises, at the temperature at which the fibers are formed, in order to facilitate continuous formation of fibers. The glass compositions are brought to a temperature sufliciently above the liquidus to insure that devitrification will not occur during fiber forming. Heat removal from the glass during fiber forming is controlled by the use of cooling devices disposed about the orifices through which the molten glass emits as a stream, see Russell Re. 24,060. The removal of heat by cooling devices is in addition to the rapid cooling inherently present in fiber forming processes because of the rapid increase in the surface area to total volume relationship which takes place in the glass as it is fiberized.

What is claimed is:

1. A fiberizable glass composition consisting of silica, alumina and bcryllia that yields high strength and high modulus to weight fibers wherein the mole percentages of each constituent of said glass composition are as follows:

Percent SiO 60-80 A1 0 8-25 BeO 8-30 2. A glass composition as described in claim 1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent SiO 63-77 A1 0 -20 BeO 9-25 3. A glass composition as described in claim 1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent SiO 70.0 A1 0 12.5 BeO 17.5

Percent SiO 70.0 A1 0 17.0 BeO 13.0

-5. A glass composition as described in claim '1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent Si0 68.6 A1 0 11.7 BeO 19.7

6. A glass composition as described in claim 1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent SiO 67.7 A1 0 14.4 BeO 17.9

7. A glass composition as described in claim 1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent SiO 70.0 A1 0 15.0 BeO 15.0

8. A glass composition as described in claim 1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent S10 65.0 A1 0 14.6 BeO 20.4

9. A glass composition as described in claim 1 that is characterized by high strength and high modulus to weight ratios wherein the mole percentages of each constituent are as follows:

Percent SiO 76.6 A1 0 13.4 BeO 10.0

10. Glass fibers formed from the glass composition of claim 1.

11. Glass fibers formed from a glass composition of claim 2.

12. Glass fibers formed from the glass composition of claim 3.

13. Glass fibers formed from the glass composition of claim 4.

14. Glass fibers formed from the glass composition of claim 5.

15. Glass fibers formed from the glass composition of claim 6.

16. Glass fibers formed from the glass composition of claim 7.

17. Glass fibers formed from the glass composition of claim 8.

18. Glass fibers formed from the glass composition of claim 9.

(References on following page) 8 References Cited Mellor, J. W., A Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol VI; Longmans, Green & UNITED STA:IES PATENTS I C0., 39 Paternoster Row, London E.C.4, 1925, pp. 802- 2,978,341 4/1961 Bastian et a1. 106-50 805. 3,127,277 3/1964 Tiede 10650 5 3,402,055 9/1968 Harris et a] "106-50 TOBIAS E-LEVOWPHmaFY Exammer M. L. BELL, Assistant Examiner OTHER REFERENCES Berry, L. G. and Mason, B., Mineralogy-Concepts, De-

scriptions, Determinations, San Francisco and London, 10 106-52 W. H. Freeman and C0., 1959, pp. 53839. 

